chore(datastore): update PR template with checkpoints

[lawmicha]

Issue #, if available:

Description of changes:
Until the integration tests are running consistently successfully in github actions, add a PR template reminder to run the integration tests manually.

Check points: (check or cross out if not relevant)

• Added new tests to cover change, if needed
• Build succeeds with all target using Swift Package Manager
• All unit tests pass
• All integration tests pass
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• If breaking change, documentation/changelog update with migration instructions

DataStore checkpoints (check when completed)

• Ran AWSDataStorePluginIntegrationTests
• Ran AWSDataStorePluginV2Tests
• Ran AWSDataStorePluginMultiAuthTests
• Ran AWSDataStorePluginCPKTests
• Ran AWSDataStorePluginAuthCognitoTests
• Ran AWSDataStorePluginAuthIAMTests

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[harsh62]

LGTM